It is well known to subject an object to electron beam (e-beam) radiation for a variety of beneficial purposes. For instance, e-beam irradiation has been widely used for such purposes including, but not limited to: (a) pharmaceutical sterilization to inactivate microorganisms either by causing microbial death as a direct effect of the destruction of a vital molecule or by an indirect chemical reaction, (b) food irradiation to target bacteria DNA, thus destroying the ability of the bacteria to reproduce or live, (c) cross-linking and molecular modification of polymeric products (e.g., wire, cable and tubing) to improve characteristics of the polymer, (d) polymer chain scission to improve properties of certain polymers by creating controlled degradation, (e) curing of adhesives and resins, and (f) treating semiconductors to control semiconductor switching speeds. Recently, e-beam radiation has found use in the efforts to protect against bioterrorism. In this regard, mail has been irradiated to neutralize any contaminants located therein.
In order to effectively monitor e-beam irradiation, and verify that an object has received appropriate exposure to the e-beam radiation, it is necessary to determine the “absorbed dose” of electron beams that are absorbed by that object. “Absorbed dose” refers to the energy imparted by ionizing radiation per unit mass of an irradiated material. Absorbed dose is commonly defined in units of J/kg, Grays, or Rads.
The present invention provides a method and apparatus for accurately measuring doses of electron beams that are absorbed by an irradiated object.